Do not spawn a thread in browser/interactive ui tests before spawning sandbox host process

content/browser/renderer_host/render_sandbox_host_linux.cc

Index: content/browser/renderer_host/render_sandbox_host_linux.cc
diff --git a/content/browser/renderer_host/render_sandbox_host_linux.cc b/content/browser/renderer_host/render_sandbox_host_linux.cc
index a018043b648c4a41cc4c8c130328ff2fb02caff9..d17b1caa7cac1e6278df29d6a7c10de8e5669cfd 100644
--- a/content/browser/renderer_host/render_sandbox_host_linux.cc
+++ b/content/browser/renderer_host/render_sandbox_host_linux.cc
@@ -709,10 +709,9 @@ void RenderSandboxHostLinux::Init(const std::string& sandbox_path) {
   childs_lifeline_fd_ = pipefds[1];
 
   // We need to be monothreaded before we fork().
-#if !defined(TOOLKIT_GTK) && !defined(OS_CHROMEOS)
+#if !defined(TOOLKIT_GTK)
   // Exclude gtk port as TestSuite in base/tests/test_suite.cc is calling
   // gtk_init.
-  // Exclude ChromeOS because KioskTest spawns EmbeddedTestServer.
   // TODO(oshima): Remove ifdef when above issues are resolved.
   DCHECK_EQ(1, base::GetNumberOfThreads(base::GetCurrentProcessHandle()));
 #endif